Micro December 2018

between the candidate and reference method. Repeatability (0.00, 0.22, 0.12 and 0.14) and 1 reproducibility (0.00, 0.31, 0.26 and 0.22) values for each contamination level indicate that the 2 method performed similarly within sample replicates and between laboratories throughout the 3 range of contamination levels. 4 5 3M Petrifilm Rapid E. coli/Coliform Count Plate & ISO Coliform 37 o C 6 7 Difference of means values (0.00, 0.08, -0.03, -0.01) for the uninoculated, low, medium and 8 high contamination levels, indicated that no statistically significant difference existed between 9 the candidate and reference method. Repeatability (0.00, 0.28, 0.09, 0.09) and reproducibility 10 (0.00, 0.34, 0.19, 0.16) values for each contamination level indicate that the method performed 11 similarly within sample replicates and between laboratories throughout the range of 12 contamination levels. 13 14 3M Petrifilm Rapid E. coli/Coliform Count Plate & ISO E. coli 37 o C 17 and high contamination levels, indicated that no statistically significant difference existed 18 between the candidate and reference method. Repeatability (0.00, 0.28, 0.12 and 0.11) and 19 reproducibility (0.00, 0.28, 0.19 and 0.14) values for each contamination level indicate that the 20 method performed similarly within sample replicates and between laboratories throughout the 21 range of contamination levels. 22 23 3M Petrifilm Rapid E. coli/Coliform Count Plate & ISO E. coli 42 o C 26 and high contamination levels, indicated that no statistically significant difference existed 27 between the candidate and reference method. Repeatability (0.00, 0.27, 0.13 and 0.14) and 28 reproducibility (0.00, 0.27, 0.15 and 0.14) values for each contamination level indicate that the 29 method performed similarly within sample replicates and between laboratories throughout the 30 range of contamination levels. 35 in regard to the performance of the candidate method. No statistically significant difference was 36 observed between the candidate method and the reference methods, when compared using a 37 difference of means of < 0.5 and a confidence interval between -0.5 and 0.5. Based on the data 38 presented, the reproducibility values obtained for all contamination levels were generally similar 39 between the candidate and reference methods, indicating that both the between-laboratory 40 variations and within-laboratory variations were consistent between the candidate and reference 41 method. These values indicate that for reproducibility, no meaningful statistical differences 42 (absolute value of <0.50 Log 10 ) were observed in the data between the candidate and reference 43 methods when test portions were analyzed by different analysts at each laboratory or within each 44 sample set at a given laboratory . 15 16 Difference of means values (0.00, 0.12, 0.01 and 0.04) for the uninoculated, low, medium 24 25 Difference of means values (0.00, 0.14, -0.05 and 0.05) for the uninoculated, low, medium 31 32 33 34 Discussion No negative feedback was reported to the study directors from the collaborating laboratories

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Recommendations

9